Electrospinning of poly(3-hydroxybutyrate) (PHB), poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV), and their blends was first carried out in chloroform at 50 degrees C on a stationary collector. The average diameter of the as-spun fiber from PHB and PHBV solutions decreased with increasing collection distance and increased with increasing solution concentration and applied electrical potential. In all of the spinning conditions investigated, the average diameter of the as-spun pure fibers ranged between 1.6 and 8.8 mu m. Electrospinning of PHB, PHBV, and their blends was carried out further at a fixed solution concentration of 14% w/v on a homemade rotating cylindrical collector. Well-aligned, cross-sectionally round fibers without beads were obtained. The average diameter of the as-spun pure and blend fibers ranged between 2.3 and 4.0 mu m. The as-spun fiber mats appeared to be more hydrophobic than the corresponding films and much improvement in the tensile strength and the elongation at break was observed for the blend fiber mats over those of the pure fiber ones. Lastly, indirect cytotoxicity evaluation of the as-spun pure and blend fiber mats with mouse fibroblasts (L929) indicated that these mats posed no threat to the cells. (c) 2006 Wiley Periodicals, Inc.